食道神経内分泌細胞腫瘍の内視鏡診断

Endoscopic Diagnosis of Esophageal Neuroendocrine Tumors

要旨●現在の「食道癌取扱い規約 第11版」では食道の神経内分泌細胞腫瘍に神経内分泌腫瘍（neuroendocrine tumor ; NET G1 or G2）と神経内分泌細胞癌（neuroendocrine carcinoma ; NEC）が含まれる．ともにまれな疾患であるが，特に食道NETは消化管NETの中でも極めてまれであり，内視鏡所見に関する報告は少ない．また遭遇する食道NECの多くは進行癌であり表在癌で見つかることはまれである．食道NECは通常型扁平上皮癌に比べて予後不良であり，化学療法のレジメンも異なることから治療前の正確な診断が要求されるが，ゴールドスタンダードである生検診断でも確定診断が得られない場合が多い．そのため本疾患の内視鏡的特徴を理解し，疑われる場合には病理医と連携してできるだけ拾い上げるように努めることが重要である．

　The Japanese Classification of Esophageal Cancer（11th edition）identified neuroendocrine tumors（NET G1 or G2）and NEC（neuroendocrine carcinoma）as esophageal neuroendocrine tumors. Both diseases rarely occur, particularly the esophageal NET, which is extremely rare among the gastrointestinal NETs ; therefore, reports regarding their endoscopic findings are limited. The characteristics of esophageal NEC are more aggressive than those of the normal types of squamous cell carcinoma. Therefore, several esophageal NECs are diagnosed as advanced cancer and rarely detected as superficial cancer. Preoperative accurate histological diagnosis is required because they have different chemotherapeutic regimens. However, some NECs cannot be accurately histologically diagnosed using biopsy specimens, the gold standard procedure. Therefore, their endoscopic features should be properly understood and, as much as possible, not be overlooked by the pathologist during the histological examination.